A variety of methods have been investigated in different laboratories for the polymerization of amino acids and nucleotides under abiotic conditions. They include (1) thermal polymerization, (2), direct polymerization of certain amino acid nitriles, amides or esters, (3) polymerization using polyphosphate esters, (4) polymerization under aqueous or drying conditions at moderate temperatures using a variety of simple catalysts or condensing agents like cyanamide, dicyandiamide, imidazole, etc., and (5) polymerization under similar mild conditions but employing activated monomers or abiotically synthesized high energy compounds such as adenosine 5′-triphosphate (ATP). The role and significance of these methods for the synthesis of oligopeptides and oligonucleotides under possible primitive Earth conditions is evaluated. It is concluded that the latter more recent approach involving chemical processes similar to those used by contemporary living organisms, appears to offer a reasonable solution to the prebiotic synthesis of these biopolymers.
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